Saliva exposure reduces gingival keratinocyte growth on TiO2-coated titanium.

Bioactive, nanoporous TiO2-coating has been shown to enhance cell attachment on titanium implant surface. The aim of this study was to evaluate, whether the saliva proteins affect the epithelial cell adhesion on TiO2-coated and non-coated titanium. Grade V titanium discs were polished. Half of the discs were provided with TiO2-coating produced in sol with polycondensation method. Half of the TiO2-coated and non-coated discs were treated with pasteurized saliva for 30 min. After saliva treatment, the total protein amounts on surfaces were measured. Next, the hydrophilicity of discs were measured with water contact angle measurements. Further, the gingival keratinocyte adhesion strength was measured after 2 and 6 h of cultivation using serial trypsinization. In addition, cell growth and proliferation were measured after 1, 3, and 7 days of cell culture. Finally, cell morphology, spreading and adhesion protein signals were detected with high resolution confocal microscopy. As a result, in sol coated TiO2-surface had significantly higher hydrophilicity when compared to non-coated titanium, meanwhile both non-coated and TiO2-coated surfaces with saliva treatment had a significant increase in hydrophilicity. Importantly, the amounts of adhered saliva proteins were equal between TiO2-coated and non-coated surfaces. Adhesion strength against enzymatic detachment was weakest on non-coated titanium after saliva exposure. Cell proliferation and cell spreading were highest on TiO2-coated titanium, but saliva exposure significantly decreased cell proliferation and spreading on TiO2-coated surface. To conclude, even though saliva exposure makes titanium surfaces more hydrophilic, it seems to neutralize the bioactive TiO2-coating and decrease cell attachment to TiO2-coated surface.

Oral erythroplakia and oral erythroplakia-like oral squamous cell carcinoma - what's the difference?

BACKGROUND: Oral erythroplakia (OE) is a rare oral potentially malignant disorder, that has a high rate of malignant transformation. The definition of OE still lacks uniformity. In particular, lesions that look clinically like erythroplakias, but are histopathologically diagnosed as squamous cell carcinomas are still sometimes called erythroplakias. The purpose of this study is to present demographic and clinicopathologic features of a series of OEs and clinically oral erythroplakia -like squamous cell carcinomas (OELSCC), to study their differences and to discuss the definition of OE. METHODS: A multicenter retrospective case series of OEs and OELSCCs. Descriptive statistics were used to analyze the data. RESULTS: 11 cases of OEs and 9 cases of OELSCCs were identified. The mean age of the OE patients was 71 years and 72.7% were female, while the mean age of the OELSCC patients was 69 years, and all were female. 9% of the OE and 22% of the OELSCC patients had smoked or were current smokers. 72.7% of the OEs and 55.5% of OELSCCs were uniformly red lesions. 63.6% of the OE and 22% of the OELSCC patients had a previous diagnosis of oral lichenoid disease (OLD). The malignant transformation rate of OE was 9% in a mean of 73 months. CONCLUSIONS: OE and OELSCC may arise de novo or in association with OLD. Tobacco and alcohol use were not prevalent in the present cases. The clinical features of OEs and OELSCC are similar, but symptoms, uneven surface and ulceration may be more common in OELSCCs than in OEs. Clinical recognition of OE is important since it may mimic other, more innocuous red lesions of the oral mucosa. The diagnosis of OE requires biopsy and preferably an excision. Clarification of the definition of OE would aid in clinical diagnostics.

Appearance and recurrence of odontogenic keratocysts.

OBJECTIVE: The purpose of this study was to evaluate the appearance, histopathological features, and recurrence of odontogenic keratocysts (OKCs) from a large single institute registry over a 36-year period. MATERIALS AND METHODS: A total of 226 cases of OKC were identified in 174 patients over a 36-year period in a single institute in Southwestern Finland. Histological specimens were re-evaluated. The patient's age, sex, location, recurrence, and histopathological features of the OKC were the study variables. RESULTS: OKCs occurred more frequently in men, the mean age was 46 years, and the most frequent site was the lower jaw. Recurrence rate was 21%. Histopathologically, inflammation was present in 95% and satellite cysts in 10% of cases. In patients diagnosed with satellite cysts, OKC recurred in 50% of cases, while the corresponding figure for patients without satellite cysts was 17%. CONCLUSIONS: Compared with the literature, patients were older and inflamed cysts were found more frequently. Satellite cysts occurred only in association with chronic inflammation. Based on the results, regular radiographic evaluation is important among patients aged 10-29 years to detect OKCs and to treat them before enlargement, infection, and inflammation. Satellite cysts should be reported and may be a sign of increased risk of OKC recurrence.

Ex vivo detection of lipopolysaccharide immunopositivity in Rushton bodies.

AIM: Our aim was to investigate how bacterial lipopolysaccharide (LPS) is immunoexpressed in periapical lesions. By surprise we detected Rushton bodies (RBs) whose origin has been debatable to be positive for LPS. METHODOLOGY: Samples of radicular cysts (N=70) were stained in order to identify variations in LPS immunoexpression indicating bacterial background. For immunostaining, we used an anti-LPS antibody from Escherichia coli, and for visualization Horse Radish Peroxidase labeled polymer as the secondary antibody. RESULTS: RBs showed positivity for LPS in radicular cysts. After collection of radicular cyst samples (70 in total), we noted that all RBs (N=25) histologically detected in tissue samples were positive for LPS. Furthermore, calcification in the cyst capsule showed immunopositivity. CONCLUSION: We demonstrate for the first time that LPS is present in RBs, indicating that host response to bacteria might be the initial cause of the formation of these hyaline bodies in the cyst epithelium and cyst capsule calcifications.

Focal adhesion formation of primary human gingival fibroblast on hydrothermally and in-sol-made TiO2 -coated titanium.

Optimal cell adhesion of the gingival fibroblasts to dental implants is important for maintaining good implant integration. The aim of this study was to discover, if the nanoporous TiO2 -coating on titanium alloy substrates is able to increase the cell adhesion of the human gingival fibroblasts (HGF). The study consisted of three differently produced titanium groups: hydrothermally produced TiO2 -coating (HT), novel TiO2 -coating made in sol (SOL), and noncoated control group. Primary HGF cells were initiated from gingival biopsies from patients having a third molar extraction. HGF were cultivated on titanium discs for 2 and 24 h to determine the initial attachment with confocal microscope. The cell spreading and adhesion protein signals were measured. In addition, expression of adhesion proteins vinculin, paxillin, and focal adhesion kinase (FAK) were measured after 3 days of cultivation by using Western Blotting. Higher protein levels of paxillin, vinculin, and FAK were induced on both coated discs compared to noncoated discs. The difference was statistically significant (p < 0.05) concerning expression of paxillin. The cell spreading was significantly larger on SOL discs after 2 and 24 h when comparing to noncoated controls. The confocal microscope analyses revealed significantly higher adhesion protein signals on both HT- and SOL-coated titanium compared to control group. This study showed, that both methods to produce TiO2 -coatings are able to increase HGF adhesion protein expression and cell spreading on titanium surface. Accordingly, the coatings can potentially improve the gingival attachment to titanium implant surfaces.

Bioactive glass air-abrasion promotes healing around contaminated implant surfaces surrounded by circumferential bone defects: An experimental study in the rat.

OBJECTIVES: The present study aimed to evaluate the healing of experimentally induced bone defects around contaminated dental implants after air-abrasion using 45S5 or zinc oxide (ZnO)-containing bioactive glasses (BAGs). MATERIALS AND METHODS: One maxillary first molar was extracted from each Sprague-Dawley rat (n = 30). After 4-week healing, a titanium implant was placed in the extraction site with a circumferential bone defect. The rats were randomized into five different groups: (1) implants with Fusobacterium nucleatum and Porphyromonas gingivalis dual-species biofilm (IB); (2) implants with biofilm subjected to inert glass air-abrasion (inert); (3) sterile implants (S); (4) implants with biofilm subjected to 45S5 BAG air-abrasion (45S5); and (5) implants with biofilm subjected to ZnO-containing BAG air-abrasion (Zn4). After 8-week healing, maxillae were dissected, and histomorphometric analyses were performed. RESULTS: The first bone-to-implant contact was significantly shorter for the inert (1.58 ± 1.16 mm; p = 0.016), S (0.28 ± 0.13 mm; p < 0.001), 45S5 (0.41 ± 0.28 mm; p < 0.001), and Zn4 (0.26 ± 0.16 mm; p < 0.001) groups compared to IB group. Also, significantly more bone-to-implant contact was seen for S (72.35% ± 8.32%; p < 0.001), 45S5 (57.91% ± 24.10%; p = 0.002), and Zn4 (70.49% ± 12.74%; p < 0.001) groups than the IB group. The bone volume with the threads demonstrated significantly higher value for S (69.32% ± 9.15%; p < 0.001), 45S5 (58.93% ± 23.53%; p = 0.001), and Zn4 (68.65% ± 12.41%; p < 0.001) groups compared to the IB group. The bone volume within the defects was significantly higher for S (68.79% ± 11.77%; p < 0.001), 45S5 (62.51% ± 20.51%; p = 0.002), and Zn4 (73.81% ± 15.07%; p < 0.001) groups compared to the IB group. CONCLUSIONS: This study suggests that air-abrasion of contaminated moderately rough implant surfaces with either 45S5 or ZnO-containing BAGs enhances osseointegration and bone defect regeneration.

Histopathological findings of oral epithelial dysplasias and their relation to malignant transformation.

OBJECTIVES: Oral squamous cell carcinomas (OSCCs) are often diagnosed late. This study aimed to determine how frequently oral epithelial dysplasia (OED) transforms to OSCC and to identify histological features that could influence the rate of malignant transformation. MATERIALS AND METHODS: The study was a retrospective analysis of OED over 29 years at the Institute of Dentistry, University of Turku, Finland. OEDs with co-existing carcinomas were excluded from the data (5.8%). OED patients who developed carcinoma were identified from the Finnish Cancer Registry database. RESULTS: Altogether 681 OED patients had a mean age of 59.0 years, and the male:female ratio was 0.67. Of all OED samples, 21.8% were on the tongue, followed by lining mucosa (21.3%), lip (5.3%), and masticatory mucosa (4.85%). In addition, 46.7% had no location cited. The prevalence of mild dysplasia was 62.4%, moderate dysplasia 29.1%, and severe dysplasia 3.2%. Of the patients, 94.7% had an additional histological diagnosis alongside OED. Candidiasis, lichenoid inflammation, and ulcer were found in 18.2%, 0.0%, and 22.7% of severe dysplasias, in 12.1%, 12.2%, and 22.7% of moderate dysplasias, and in 6.6%, 12.2%, and 15.8% of mild dysplasias, respectively. An additional histopathological diagnosis did not increase the risk for OED to transform to OSCC. In a mean time of 5.2 (range 0.7-29.0) years, 7.5% of OED patients developed OSCC. CONCLUSIONS: Location on the tongue and the more severe OED grades increased the risk of malignant transformation of OED. These patients may benefit from an intensified follow-up schedule to ensure early diagnosis of OSCC.

Oncocytic variant of sialadenoma papilliferum - a rare salivary gland tumor: A case report.

Background: Sialadenoma papilliferum (SP) is a rare minor salivary gland neoplasm that accounts for less than 1% of all salivary gland tumors. The tumor typically affects older people, presenting most commonly as a slow-growing tumor of the hard palate, although other anatomical subsites, comprising the oral cavity and parotid glands, have also been reported. Case Report: We report a SP occurring in a 90-year-old female. The patient described feeling a nodule on her palate for several years. The lesion was painless and clinically resembled a round craterlike ulceration of diameter 3 mm. The excisional biopsy was diagnosed histologically as SP. Here, we report the clinicopathological and radiological findings of palatal SP. Conclusions: SP is a rare, benign salivary gland neoplasm, and there are only a few cases described in the literature. Although mostly benign, malignant transformation can occur and should prompt the clinician to ensure complete removal of the tumor tissue. Key words:Sialadenoma papilliferum, minor salivary gland tumor, histopathology, oral pathology, case report.

Epithelial cell attachment and adhesion protein expression on novel in sol TiO2 coated zirconia and titanium alloy surfaces.

An adequate mucosal attachment is important when it comes to preventing peri-implant inflammation. The aim of this study was to compare epithelial cell adhesion and adhesion protein expression on in sol TiO2 -coated and non-coated zirconia and titanium alloy surfaces. Fifty-six zirconia and titanium discs were cut, and half of them were coated with bioactive TiO2 -coating. To study the epithelial cell attachment, human gingival keratinocytes were cultivated on discs for 1, 3, 6, and 24 h. The cell proliferation was detected by cultivating cells for 1, 3, and 7 days. In addition, the levels of adhesion proteins laminin y2, integrin α6, ß4, vinculin, and paxillin were detected with Western Blot method. Furthermore, high-resolution imaging of the actin cytoskeleton and focal adhesion proteins was established. Longer-term cell culture (1-7 days) revealed higher cell numbers on the coated zirconia and titanium discs compared to non-coated discs. The difference was statistically significant (p < .05) after 24 h on coated zirconia and after 3 and 7 days on coated titanium discs compared to non-coated discs. Clear induction in the protein levels of laminin y2 and integrin α6 were detected on both coated samples, meanwhile integrin ß4 were clearly induced on coated titanium alloy. The microscope evaluation showed significantly increased cell spreading on the coated discs. According to this study, the in sol induced TiO2 -coating increases keratinocyte attachment and the expression of adhesion proteins on coated zirconia and titanium in vitro. Consequently, the coating has potential to enhance the mucosal attachment on implant surfaces.

Organotypic in vitro block culture model to investigate tissue-implant interface. An experimental study on pig mandible.

In vitro studies of implant-tissue attachment are primarily based on two-dimensional cell culture models, which fail to replicate the three-dimensional native human oral mucosal tissue completely. Thus, the present study aimed to describe a novel tissue culture model using pig mandibular block including alveolar bone and gingival soft tissues to evaluate the tissue attachment to titanium implant provided with hydrothermally induced TiO2 coating. Tissue attachment on TiO2 coated and non-coated implants were compared. Ti-6Al-4V alloy posts were used to function as implants that were inserted in five pig mandibles. Implants were delivered with two different surface treatments, non-coated (NC) titanium and hydrothermal induced TiO2 coated surfaces (HT). The tissue-implant specimens were cultured at an air/liquid interface for 7 and 14 days. The tissue-implant interface was analyzed by histological and immunohistochemical stainings. The microscopic evaluation suggests that pig tissue explants established soft and hard tissue attachment to both implant surfaces. The epithelial cells appeared to attach to the coated implant. The epithelium adjacent to the implant abutment starts to change its phenotype during the early days of the healing process. New bone formation was seen within small pieces of bone in close contact with the coated implant. In conclusion, this in vitro model maintains the viability of pig tissue and allows histologically and immunohistochemically evaluate the tissue-implant interface. HT-induced TiO2 coating seems to have a favorable tissue response. Moreover, this organotypic tissue culture model is applicable for further studies with quantitative parameters to evaluate adhesion molecules present at the implant-tissue interface.

Oral Human Papillomavirus Infection in Children during the First 6 Years of Life, Finland.

Human papillomavirus (HPV) infections are found in children, but transmission modes and outcomes are incompletely understood. We evaluated oral samples from 331 children in Finland who participated in the Finnish Family HPV Study from birth during 9 follow-up visits (mean time 51.9 months). We tested samples for 24 HPV genotypes. Oral HPV prevalence for children varied from 8.7% (at a 36-month visit) to 22.8% (at birth), and 18 HPV genotypes were identified. HPV16 was the most prevalent type to persist, followed by HPV18, HPV33, and HPV6. Persistent, oral, high-risk HPV infection for children was associated with oral HPV carriage of the mother at birth and seroconversion of the mother to high-risk HPV during follow-up (odds ratio 1.60-1.92, 95% CI 1.02-2.74). Children acquire their first oral HPV infection at an early age. The HPV status of the mother has a major impact on the outcome of oral HPV persistence for her offspring.

Zirconia implants with improved attachment to the gingival tissue.

BACKGROUND: Gingival tissue attachment is known to be important for long-term prognosis of implants. This in vitro study evaluated the gingival attachment to zirconia implants and zirconia implants modified with sol-gel derived TiO2 coatings. METHODS: Zirconia endodontic posts (n = 23) were used to function as implants that were inserted into the center of full-thickness porcine gingival explants (n = 31). The tissue/implant specimens were then individually placed at an air/liquid interface on a stainless-steel grid in cell culture wells containing a nutrient solution. The tissue cultures were incubated at 37°C in a 5% CO2 environment and at days 7 and 14, the specimens were harvested and analyzed by dynamic mechanical analysis (DMA) measurements under dynamic loading conditions mimicking natural mastication. Specimens were also analyzed by immunohistochemical staining identifying the laminin (Ln) γ2 chain specific for Ln-332, which is known to be a crucial molecule for the proper attachment of epithelium to tooth/implant surface. RESULTS: Tissue attachment to TiO2 -coated zirconia demonstrated higher dynamic modulus of elasticity and higher creep modulus, meaning that the attachment is stronger and more resistant to damage during function over time. Laminin γ2 was identified in the attachment of epithelium to TiO2 -coated zirconia. CONCLUSIONS: Both DMA and histological analysis support each other, so the gingival tissue is more strongly attached to sol-gel derived TiO2 -coated zirconia than uncoated zirconia. Immunohistochemical staining showed that TiO2 coating may enhance the synthesis and deposition of Ln-332 in the epithelial attachment to the implant surface.

TiO2-Modified Zirconia Surface Improves Epithelial Cell Attachment.

PURPOSE: Good cell adhesion is an important prerequisite for soft tissue attachment on implant abutment or crown surfaces. The aim of this study was to evaluate the adhesion and proliferation of human epithelial cells on sol-gel-derived TiO2-coated and noncoated zirconia. MATERIALS AND METHODS: Altogether, 56 zirconia disks (Z-CAD, Metoxit) were fabricated for this study. Half of the disks were coated with a sol-gel-derived TiO2 coating (MetAlive, ID Creations). The rest of the disks were noncoated and formed the control group. Surface properties of the disks were characterized by contact angle measurements and surface free energy (SFE) calculation. The cell adhesion was tested by cultivating epithelial cells (20,000 cells/cm2) on the experimental disks for 1, 3, 6, and 24 hours, after which the fluorescence of the samples was measured (BioTek synergy HT). The amount of cells was detected by comparing the fluorescence value to the standard curve. In addition, the proliferation was studied by growing epithelial cells (25,000 cells/cm2) for 1, 3, and 7 days. The number of cells was calculated by defining the absorbance of the samples (Multiskan EX, Thermo Labsystems), followed by a comparison with the standard curve. Finally, the samples were processed for light microscopy. RESULTS: TiO2-coated disks were significantly more hydrophilic with higher total SFE than noncoated disks (P < .05). The amount of epithelial cells was greater on TiO2-coated disks than on controls after 24 hours (P < .05). Regarding cell proliferation, the difference was statistically significant (P < .05) on days 3 and 7. Light microscope evaluation confirmed viable cells, which were in immediate close contact with both substrate surfaces. The cell layers on the coated disks appeared to be more uniform and cell rich than the layers on noncoated disks. CONCLUSION: This study indicated that TiO2 coating improves epithelial cell attachment and proliferation on zirconia surfaces. This has good potential to enhance formation of the epithelial junction to the coated zirconia surfaces.

In vitro assessment of the soft tissue/implant interface using porcine gingival explants.

The biologic seal of peri-implant soft tissue is crucial for long-term prognosis of oral implants. This in vitro study describes a novel tissue culture model using porcine gingival explants to evaluate the soft tissue/implant interface. Two different types of substrates were investigated: (a) plain polymer: BisGMA-TEGDMA (50-50 %) and (b) unidirectional fiber-reinforced composite (FRC). Porcine gingival explants were obtained from a local slaughterhouse. The experimental implants (n = 4) were inserted into the middle of freshly excised porcine gingival explants and cultured at the air/liquid interface up to 14 days. Porcine gingival explants with no implants served as baseline controls. The specimens were fixed and processed for the preparation of undecalcified samples. Histological analysis of the soft tissue/implant interface was carried out using a light-microscope. Microscopic evaluation suggests that the gingival explants established epithelial and connective tissue attachment to both implant types over the incubation period. FRC surfaces seemed to have a favorable tissue response with a sign of an outward epithelial migration. However, tissue degeneration was observed at the end of the experiment. In conclusion, this in vitro model maintains mucosal viability and ability to histologically evaluate soft tissue attachment to biomaterials rendering it a time efficient and cost effective model that may reduce the need for animal experiments.

Genotype-specific incidence and clearance of human papillomavirus in oral mucosa of women: a six-year follow-up study.

BACKGROUND: There are no previous longitudinal studies on genotype-specific natural history of human papillomavirus (HPV) infections in oral mucosa of women. METHODS: In the Finnish Family HPV Study, 329 pregnant women were enrolled and followed up. HPV-genotyping of oral scrapings was performed with nested PCR and Multimetrix® test (Progen, Heidelberg, Germany). Incidence and clearance times and rates for each HPV-genotype identified in oral mucosa were determined. Predictors for incident and cleared HPV infections for species 7/9 genotypes were analyzed using Poisson regression model. RESULTS: Altogether, 115 baseline HPV-negative women acquired incident oral HPV infection, and 79 women cleared their infection. HPV16 and multiple HPVs most frequently caused incident infections (65% and 12%) in 13.3 and 17.1 months respectively, followed by HPV58, HPV18 and HPV6 (close to 5% each) in 11-24 months. HPV58, HPV18 and HPV66 were the most common to clear. HPV6 and HPV11 had the shortest clearance times, 4.6 months and 2.5 months, and the highest clearance rates, 225.5/1000 wmr and 400/1000 wmr, respectively. The protective factors for incident oral HPV-species 7/9 infections were 1) new pregnancy during follow-up and 2) having the same sexual partner during FU. Increased clearance was related with older age and a history of atopic reactions, whereas previous sexually transmitted disease and new pregnancy were associated with decreased clearance. CONCLUSIONS: HPV16 was the most frequent genotype to cause an incident oral HPV-infection. Low risk HPV genotypes cleared from oral mucosa more quickly than high risk HPV genotypes. Pregnancy affected the outcome of oral HPV infection.

Prevalence, genotype distribution and persistence of human papillomavirus in oral mucosa of women: a six-year follow-up study.

BACKGROUND: Human papillomavirus (HPV) infections have been linked to a subset of oral and oropharyngeal cancers. However, little is known on the natural history of oral HPV infections. We designed the prospective Finnish HPV Family Study to assess the dynamics of HPV infections in parents and their infants. This study reports HPV genotype distribution and virus persistence in oral mucosa of the mothers. MATERIALS AND METHODS: Totally, 324 pregnant women were enrolled at the 3(rd) trimester of pregnancy and followed-up for 6 years. Oral scrapings taken with a brush were collected and HPV-genotyping was performed with nested PCR and Multimetrix® test (Progen, Heidelberg, Germany). The predictors of persistent oral HPV species 7/9 infections were analyzed using generalized estimating equation models. RESULTS: The point prevalence of oral HPV varied from 15% to 24% during the 6-year follow-up. Altogether, 18 HPV genotypes were identified either as single or multiple-type oral infections. HPV16 was the most prevalent type at 9.7%-18.4%, followed by HPV18, HPV6, and multiple infections. Altogether, 74 women had persistent oral HPV infection determined as at least two consecutive samples positive with the same HPV genotype. HPV16 and HPV6 were the two most frequent types to persist (76% and 9%) for a mean of 18.6 and 20.2 months, respectively, followed by multiple infections (8%) for 18.3 months. An increased risk for persistent oral HPV infection with species 7/9 was associated with being seropositive for low-risk (LR)-HPV-types at baseline, whereas the use of oral contraceptives and a second pregnancy during follow-up were protective. Clinical oral lesions were detected in 17% of these women, one-third of whom had persistent oral HPV-infections. CONCLUSION: HPV16 and HPV6 were the most common genotypes in oral HPV-infections and were also most likely to persist. Use of oral contraceptives and a second pregnancy protected against oral HPV persistence.

Lutheran blood group antigen as a receptor for alpha5 laminins in gingival epithelia.

BACKGROUND: Lutheran blood group glycoprotein (Lu) is a transmembrane receptor of the immunoglobulin superfamily. Lu serves as a receptor for alpha5 laminins (Lm). The Lm alpha5 chain is a constituent of Lms-511 and -521. Lm-511 is found in most human basement membranes (BMs) and also is detected in BM of gingival epithelia. Recent studies indicated that Lu mediates cell adhesion to Lms-511/521 independently or in concert with integrins. This study focused on the expression of Lu in gingival epithelia and on cultured immortalized gingival keratinocytes. The role of Lu and alpha(3) and beta(1) integrin subunits in the adhesion of oral epithelial cells to Lms-511/521 was also studied. METHODS: Immunofluorescence microscopy was used to study the expression of Lu in gingival tissues and in cultured gingival keratinocytes. Immunoprecipitation of radioactively metabolically labeled cells was used to detect Lu. Cell adhesion to Lm-511/521 preparation and to pure Lm-511 was studied in quantitative cell adhesion experiments. Morphological adhesion assays were carried out for visualization of the morphology and adhesion structure formation of the adhering cells. RESULTS: Immunofluorescence studies on gingiva showed complete coalignment of Lu on basal epithelial cells with the BM Lm alpha5 chain. A surface-confined, punctate immunoreaction for Lu was detected throughout cell surfaces on cultured gingival cells. Immunoprecipitation showed a broad polypeptide with molecular weight 85,000. In quantitative cell adhesion assays, the adhesion of cells to both Lm alpha5 preparations was diminished with monoclonal antibodies (MAbs) against integrin alpha(3) and even more effectively with MAbs against the beta(1) subunit. When the adhesion sites were blocked with soluble recombinant Lu (sol-Lu), the adhesion of gingival epithelial cells to Lms-511/521 was reduced significantly, and sol-Lu increased the inhibition with integrin alpha(3) antibody. Lm-511 did not induce lamellipodia or focal contacts in cultured gingival keratinocytes. CONCLUSIONS: Lu was in coalignment with Lm alpha5 chain in gingival epithelia. Lu also seemed to have a role in gingival epithelial cell adhesion together with integrin alpha(3)beta(1).

Junctional epithelium in rats is characterized by slow cell proliferation.

BACKGROUND: The integrity of junctional epithelium (JE) and a firm epithelial adhesion to the tooth surface are maintained by the balance between cell proliferation and cell death. Maintaining the JE structure is essential for the protection of periodontal connective tissues against oral microbes. In this study, the proliferative activity and the expression of caspase 3, a cysteine protease associated with cell death, were studied in rat JE and other epithelial structures during molar tooth development. METHODS: Fourteen rats aged 10 to 70 days were injected with bromodeoxyuridine (BrdU). Samples of first and second molars were selected for immunohistochemical staining. BrdU incorporation was studied in oral epithelium (OE) covering the erupting tooth, reduced enamel epithelium (REE), and gingival epithelium (GE), sulcular epithelium (SE), and JE. Samples were also subjected to immunohistochemical analysis for proliferating cell nuclear antigen (PCNA) and caspase 3. RESULTS: The basal cells of the GE were actively proliferating, but in the JE, only a few cells were positive for BrdU or PCNA immunostaining. Some outer REE cells were proliferating during tooth eruption. Caspase 3 expression was in specific areas of REE after completion of amelogenesis. CONCLUSIONS: Results showed slow proliferative activity in the rat JE. However, specific studies on cellular turnover and cell migration are needed to understand tissue homeostasis in this area.

Marginal periodontium as a potential reservoir of human papillomavirus in oral mucosa.

BACKGROUND: Although human papillomaviruses (HPVs) are associated with a number of proliferative epithelial lesions including squamous cell malignancies, they can also be detected in the normal oral mucosa in 10% to 20% of the adult population. However, the point of entry and the site of replication of HPV in the oral cavity are not known. Since the gingival pocket is the only site in the oral mucosa where basal cells, known to be targets of HPV at other mucosal sites, are normally exposed to the environment, we hypothesized that this could be the site of latent HPV. METHODS: Gingival biopsies taken from 38 individuals with clinically diagnosed periodontal disease were examined. The presence of HPV DNA was studied by using nested PCR (polymerase chain reaction with MY09/MY11 and GP05+/GP06+ primers targeting the L1 region of HPV), followed by subsequent hybridization with a cocktail of 12 high-risk HPV oligoprobes and in situ hybridization (ISH) with probes for HPV screening and the HPV subtype 16. RESULTS: In the present study, high-risk HPV types were detected in 26% (8/31) of the gingival biopsies with PCR. By using in situ hybridization, the viral DNA was localized to the coronal part of the junctional epithelium in the gingival pocket. CONCLUSIONS: The results suggest that the periodontal pocket might serve as a reservoir of HPVs in oral mucosa. While having important implications in understanding the HPV transmission, this observation does not rule out the possibility that HPV may be involved in the initiation of periodontal disease.